Rear light bulbs: tail light out, melted holders and blowing bulbs

Tail light out: what to check, in order

The 2004 thread started with a tail light that was out while the brake light still worked. The checks owners gave:

1. Swap the bulb with the one from the other side. The tail and brake lamps share one twin filament bulb. A bulb can have one filament gone and the other fine, and filaments don't always blow in an obvious way.
2. Check it is the right way round. One owner said that fitted back to front you can get very bright tail lamps and a dim brake light, and that it might blow the fuse (his experience, not confirmed elsewhere).
3. Check the fuse. One owner said it is a 7.5 A fuse and suggested swapping it with a known good one. The NA fuse chart lists "stop lamp / reversing lamp" as 7.5 A: see relays and fuses. Another owner pointed out that if only one side is out, the fuse is unlikely to be the cause.
4. Check the wiring and connectors. It is easy to knock a wire when you stuff things into the boot. Look for oxidation or rust on the connections and clean them.
5. Brake light works, tail light doesn't: one owner thought the connector unlikely and put his money on the bulb. In the thread the original poster found it was just a bulb.

Reversing light. Two owners had a reversing light that was dead for a different reason: the reverse switch on the gearbox. In one case the bulb, fuse and wiring were all fine and replacing the switch fixed it. Nobody in the thread said how to get at or replace the switch.

Intermittent. One owner noticed his light wasn't working, then found it working again when he looked at home. He suspected a loose filament. It is possible, but the thread doesn't say how it ended.

Taking the rear cluster out

• The cluster comes out from inside the boot. Use a torch and a small socket set (2010 owners).
• Four M5 nuts on each cluster, so an 8 mm socket (one owner). Another owner remembered three on each side, so count them on your car.
• The unit also has double-sided tape holding it.
• Go easy on the nuts, and when refitting. The plastic can be brittle and the threaded studs can pull out.
• An owner reckoned about an hour. He had done the front lights many times and said the rear was no harder.

See also rear clam removal if you are doing more at the back of the car.

New bulb won't go in: the melted holder (2010 and 2011)

In 2010 an owner found that his driver-side rear bulb holder had melted around the old bulb. The plastic had reformed around the base, so he had to smash the bulb to get it out, and then a new bulb wouldn't fit. He had the bulb replaced by someone else shortly before and wondered if it had been fitted badly. Then about a dozen other owners said it had happened to them as well, some on both sides. The thread had no hard answer on cause, only the cures.

• Remove the cluster first if you can. Two owners who filed or chiselled with it in place got debris in the housing (white specks, or dust on the visible side of the lens) that wouldn't come out.
• Cut or file the molten plastic away until the bulb passes through. The tools owners used were a chisel, a large round file, a small file, and a Dremel or drill.
• The forced option: one owner held the new bulb in and pushed until the reformed plastic softened enough to let it through. Another said he smashed the bulb on the second side, so this can go wrong.
• Or fit a replacement holder. Two owners had spare holders or a loom. We haven't seen a part number.
• After filing, check the holder still twists and locks. One owner could fit the bulb but not close the holder.

Causes suggested. A bulb that was not fully seated, a poor design, and heat from sitting with your foot on the brake at traffic lights. The last one is only one owner's tongue-in-cheek advice, but another said the lamps get very hot if they stay lit for long.

Bulbs blowing and melting the housing (Turbo, 2003 to 2005)

In late 2004 and early 2005 several owners of 2003 Turbos reported that the twin filament bulb on the driver's side kept blowing, sometimes exploding, and melting the plastic housing so that a new bulb wouldn't go in.

• Who: at least five owners, all 2003 cars as far as the thread says, and most on the driver's side. One owner said the brake and driving light went at the same time. Another had just a normal single failure, once in 20,000 miles, so not every blown bulb is this fault.
• Repairs tried: new bulbs, then whole new light units, and on one car the interior wiring loom (said to be about £1,500 in parts plus three days of labour). That owner said the lights kept failing after earlier fixes, so replacing parts did not always cure it. We don't know whether the loom fixed it.
• No known fix: one owner said a wiring change had stopped the bulbs blowing on his car, and another said it hadn't cured his. Nobody described what the change was, so we can't give a fix. If you have this problem, see the notes below on checking the wiring.
• Condensation: one owner had a lot of water in the rear lenses on his car because the unit seams weren't sealed, and thought water might be involved in another case.
• Voltage: a reader asked someone with the problem to measure the voltage across the brake bulb with the engine at about 3,000 rpm and the brake pressed, both DC and AC, ideally with an oscilloscope, to look for spikes. Nobody posted a result.

LED rear bulbs

• One owner fitted LED bulbs in 2010. They come on brighter and faster, but his high-level brake light then glowed faintly all the time. He swapped one side back to a normal bulb for the MOT and changed it again afterwards.
• Another owner warned they may not be E-marked, so are not road legal, and that the light is often very directional, which is a risk if someone says they couldn't see your brake lights. These are opinions, not tested findings.
• Bulb types and the HID and LED discussion: Bulb types and upgrades.